The present invention relates to detection of tissues with labeled steroids and in particular, to radiochemical-guided surgery.
The use of conjugates of diagnostic of therapeutic agents, such as drugs, toxins and radionuclides to an antibody have been disclosed as being useful in the detection or treatment of various diseases. For example, U.S. Pat. No. 4,348,376 discloses the use of radiolabeled antibodies to carcinoembryonic antigen (CEA) to locate and diagnose CEA-containing tumors. U.S. Pat. No. 4,782,840, for example, discloses a surgical procedure (radio-immunoguided surgery) for the removal of neoplastic tissue where an animal is administered an antibody specific for neoplastic tissue where the antibody is labeled with a radioactive isotope, detecting the radiation emitted from the neoplastic tissue and surgically removing the tissue associated with the radioactivity.
A fundamental issue for a radiolabeled diagnostic agent is resolution: the ability to determine that the target tissue has a higher concentration of radioactivity than the surrounding nontarget tissue. The radiolabeled diagnostic agent should thus have a high affinity for a receptor moiety as well as retention at the tissue or organ of interest over time.
The use of radiolabeled antibodies for diagnosis or therapy has several disadvantages including the uptake of the labeled antibody by non-targeted tissues which results in a decrease in the resolution. The use of antibodies which are of murine origin also raises the possibility of a human anti-mouse antibody response. A technical difficulty on the use of radiolabeled antibodies for diagnosis or for radio-immunoguided surgery is it can take 10 days, and typically longer, to allow non-target tissue and blood pool counts to drop to a level where the targeted tissue can be differentiated with a high degree of confidence.
It would therefore be advantageous to have a compound for use in radio-guided surgery or radiodiagnostics which has a high affinity for a cellular receptor, gives good target-to-nontarget ratios, has a high specific activity and clears relatively quickly from non-target tissue and blood pools.